Note 3 - Operations and Segmentation - Summary of Freight and Other Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenue from Contract with Customer, Excluding Assessed Tax	$ 6,031	$ 6,056
Bulk [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	1,817	1,897
Industrial [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	2,104	2,017
Premium [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	1,695	1,742
Cargo and Freight [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	5,616	5,656
Other Subsidiary Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	217	235
Accessorial Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	174	151
Other Miscellaneous Product and Service Revenues [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 24	$ 14